path: root/src/common/socket.cpp

#include "socket.hpp"

#include <arpa/inet.h>
#include <netinet/tcp.h>
#include <sys/socket.h>
//#include <sys/types.h>

#include <fcntl.h>
#include <unistd.h>

#include <cstdlib>
#include <cstring>
#include <ctime>

#include "../io/cxxstdio.hpp"
//#include "mmo.hpp"
#include "utils.hpp"

#include "../poison.hpp"

static
fd_set readfds;
int fd_max;

static
const uint32_t RFIFO_SIZE = 65536;
static
const uint32_t WFIFO_SIZE = 65536;

#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wold-style-cast"
std::array<std::unique_ptr<Session>, FD_SETSIZE> session;
#pragma GCC diagnostic pop

/// clean up by discarding handled bytes
inline
void RFIFOFLUSH(Session *s)
{
    really_memmove(&s->rdata[0], &s->rdata[s->rdata_pos], RFIFOREST(s));
    s->rdata_size = RFIFOREST(s);
    s->rdata_pos = 0;
}

/// how much room there is to read more data
inline
size_t RFIFOSPACE(Session *s)
{
    return s->max_rdata - s->rdata_size;
}


/// Discard all input
static
void null_parse(Session *s);
/// Default parser for new connections
static
void (*default_func_parse)(Session *) = null_parse;

void set_defaultparse(void (*defaultparse)(Session *))
{
    default_func_parse = defaultparse;
}

/// Read from socket to the queue
static
void recv_to_fifo(Session *s)
{
    if (s->eof)
        return;

    ssize_t len = read(s->fd, &s->rdata[s->rdata_size],
                        RFIFOSPACE(s));

    if (len > 0)
    {
        s->rdata_size += len;
        s->connected = 1;
    }
    else
    {
        s->eof = 1;
    }
}

static
void send_from_fifo(Session *s)
{
    if (s->eof)
        return;

    ssize_t len = write(s->fd, &s->wdata[0], s->wdata_size);

    if (len > 0)
    {
        s->wdata_size -= len;
        if (s->wdata_size)
        {
            really_memmove(&s->wdata[0], &s->wdata[len],
                     s->wdata_size);
        }
        s->connected = 1;
    }
    else
    {
        s->eof = 1;
    }
}

static
void null_parse(Session *s)
{
    PRINTF("null_parse : %d\n", s);
    RFIFOSKIP(s, RFIFOREST(s));
}


static
void connect_client(Session *ls)
{
    struct sockaddr_in client_address;
    socklen_t len = sizeof(client_address);

    int fd = accept(ls->fd, reinterpret_cast<struct sockaddr *>(&client_address), &len);
    if (fd == -1)
    {
        perror("accept");
        return;
    }
    if (fd >= SOFT_LIMIT)
    {
        FPRINTF(stderr, "softlimit reached, disconnecting : %d\n", fd);
        shutdown(fd, SHUT_RDWR);
        close(fd);
        return;
    }
    if (fd_max <= fd)
    {
        fd_max = fd + 1;
    }

    const int yes = 1;
    /// Allow to bind() again after the server restarts.
    // Since the socket is still in the TIME_WAIT, there's a possibility
    // that formerly lost packets might be delivered and confuse the server.
    setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof yes);
    /// Send packets as soon as possible
    /// even if the kernel thinks there is too little for it to be worth it!
    /// Testing shows this is indeed a good idea.
    setsockopt(fd, IPPROTO_TCP, TCP_NODELAY, &yes, sizeof yes);

    // Linux-ism: Set socket options to optimize for thin streams
    // See http://lwn.net/Articles/308919/ and
    // Documentation/networking/tcp-thin.txt .. Kernel 3.2+
#ifdef TCP_THIN_LINEAR_TIMEOUTS
    setsockopt(fd, IPPROTO_TCP, TCP_THIN_LINEAR_TIMEOUTS, &yes, sizeof yes);
#endif
#ifdef TCP_THIN_DUPACK
    setsockopt(fd, IPPROTO_TCP, TCP_THIN_DUPACK, &yes, sizeof yes);
#endif

#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wold-style-cast"
    FD_SET(fd, &readfds);
#pragma GCC diagnostic pop

    fcntl(fd, F_SETFL, O_NONBLOCK);

    session[fd] = make_unique<Session>();
    Session *s = session[fd].get();
    s->fd = fd;
    s->rdata.new_(RFIFO_SIZE);
    s->wdata.new_(WFIFO_SIZE);

    s->max_rdata = RFIFO_SIZE;
    s->max_wdata = WFIFO_SIZE;
    s->func_recv = recv_to_fifo;
    s->func_send = send_from_fifo;
    s->func_parse = default_func_parse;
    s->client_ip = IP4Address(client_address.sin_addr);
    s->created = TimeT::now();
    s->connected = 0;
}

Session *make_listen_port(uint16_t port)
{
    struct sockaddr_in server_address;
    int fd = socket(AF_INET, SOCK_STREAM, 0);
    if (fd == -1)
    {
        perror("socket");
        return nullptr;
    }
    if (fd_max <= fd)
        fd_max = fd + 1;

    fcntl(fd, F_SETFL, O_NONBLOCK);

    const int yes = 1;
    /// Allow to bind() again after the server restarts.
    // Since the socket is still in the TIME_WAIT, there's a possibility
    // that formerly lost packets might be delivered and confuse the server.
    setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof yes);
    /// Send packets as soon as possible
    /// even if the kernel thinks there is too little for it to be worth it!
    // I'm not convinced this is a good idea; although in minimizes the
    // latency for an individual write, it increases traffic in general.
    setsockopt(fd, IPPROTO_TCP, TCP_NODELAY, &yes, sizeof yes);

    server_address.sin_family = AF_INET;
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wold-style-cast"
#if __GNUC__ > 4 || __GNUC_MINOR__ >= 8
# pragma GCC diagnostic ignored "-Wuseless-cast"
#endif
    server_address.sin_addr.s_addr = htonl(INADDR_ANY);
    server_address.sin_port = htons(port);
#pragma GCC diagnostic pop

    if (bind(fd, reinterpret_cast<struct sockaddr *>(&server_address),
              sizeof(server_address)) == -1)
    {
        perror("bind");
        exit(1);
    }
    if (listen(fd, 5) == -1)
    {                           /* error */
        perror("listen");
        exit(1);
    }

#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wold-style-cast"
    FD_SET(fd, &readfds);
#pragma GCC diagnostic pop

    session[fd] = make_unique<Session>();
    Session *s = session[fd].get();
    s->fd = fd;

    s->func_recv = connect_client;
    s->created = TimeT::now();
    s->connected = 1;

    return s;
}

Session *make_connection(IP4Address ip, uint16_t port)
{
    struct sockaddr_in server_address;
    int fd = socket(AF_INET, SOCK_STREAM, 0);
    if (fd == -1)
    {
        perror("socket");
        return nullptr;
    }
    if (fd_max <= fd)
        fd_max = fd + 1;

    const int yes = 1;
    /// Allow to bind() again after the server restarts.
    // Since the socket is still in the TIME_WAIT, there's a possibility
    // that formerly lost packets might be delivered and confuse the server.
    setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof yes);
    /// Send packets as soon as possible
    /// even if the kernel thinks there is too little for it to be worth it!
    // I'm not convinced this is a good idea; although in minimizes the
    // latency for an individual write, it increases traffic in general.
    setsockopt(fd, IPPROTO_TCP, TCP_NODELAY, &yes, sizeof yes);

    server_address.sin_family = AF_INET;
    server_address.sin_addr = in_addr(ip);
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wold-style-cast"
#if __GNUC__ > 4 || __GNUC_MINOR__ >= 8
# pragma GCC diagnostic ignored "-Wuseless-cast"
#endif
    server_address.sin_port = htons(port);
#pragma GCC diagnostic pop

    fcntl(fd, F_SETFL, O_NONBLOCK);

    /// Errors not caught - we must not block
    /// Let the main select() loop detect when we know the state
    connect(fd, reinterpret_cast<struct sockaddr *>(&server_address),
             sizeof(struct sockaddr_in));

#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wold-style-cast"
    FD_SET(fd, &readfds);
#pragma GCC diagnostic pop

    session[fd] = make_unique<Session>();
    Session *s = session[fd].get();
    s->fd = fd;
    s->rdata.new_(RFIFO_SIZE);
    s->wdata.new_(WFIFO_SIZE);

    s->max_rdata = RFIFO_SIZE;
    s->max_wdata = WFIFO_SIZE;
    s->func_recv = recv_to_fifo;
    s->func_send = send_from_fifo;
    s->func_parse = default_func_parse;
    s->created = TimeT::now();
    s->connected = 1;

    return s;
}

void delete_session(Session *s)
{
    if (!s)
        return;

    int fd = s->fd;
    // If this was the highest fd, decrease it
    // We could add a loop to decrement fd_max further for every null session,
    // but this is cheap and good enough for the typical case
    if (fd == fd_max - 1)
        fd_max--;
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wold-style-cast"
    FD_CLR(fd, &readfds);
#pragma GCC diagnostic pop
    {
        s->rdata.delete_();
        s->wdata.delete_();
        s->session_data.reset();
        session[fd].reset();
    }

    // just close() would try to keep sending buffers
    shutdown(fd, SHUT_RDWR);
    close(fd);
}

void realloc_fifo(Session *s, size_t rfifo_size, size_t wfifo_size)
{
    if (s->max_rdata != rfifo_size && s->rdata_size < rfifo_size)
    {
        s->rdata.resize(rfifo_size);
        s->max_rdata = rfifo_size;
    }
    if (s->max_wdata != wfifo_size && s->wdata_size < wfifo_size)
    {
        s->wdata.resize(wfifo_size);
        s->max_wdata = wfifo_size;
    }
}

void WFIFOSET(Session *s, size_t len)
{
    if (s->wdata_size + len + 16384 > s->max_wdata)
    {
        realloc_fifo(s, s->max_rdata, s->max_wdata << 1);
        PRINTF("socket: %d wdata expanded to %zu bytes.\n", s, s->max_wdata);
    }
    if (s->wdata_size + len + 2048 < s->max_wdata)
        s->wdata_size += len;
    else
        FPRINTF(stderr, "socket: %d wdata lost !!\n", s), abort();
}

void do_sendrecv(interval_t next_ms)
{
    fd_set rfd = readfds, wfd;
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wold-style-cast"
    FD_ZERO(&wfd);
#pragma GCC diagnostic pop
    for (int i = 0; i < fd_max; i++)
    {
        if (session[i] && session[i]->wdata_size)
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wold-style-cast"
            FD_SET(i, &wfd);
#pragma GCC diagnostic pop
    }
    struct timeval timeout;
    {
        std::chrono::seconds next_s = std::chrono::duration_cast<std::chrono::seconds>(next_ms);
        std::chrono::microseconds next_us = next_ms - next_s;
        timeout.tv_sec = next_s.count();
        timeout.tv_usec = next_us.count();
    }
    if (select(fd_max, &rfd, &wfd, NULL, &timeout) <= 0)
        return;
    for (int i = 0; i < fd_max; i++)
    {
        Session *s = session[i].get();
        if (!s)
            continue;
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wold-style-cast"
        if (FD_ISSET(i, &wfd))
#pragma GCC diagnostic pop
        {
            if (s->func_send)
                //send_from_fifo(i);
                s->func_send(s);
        }
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wold-style-cast"
        if (FD_ISSET(i, &rfd))
#pragma GCC diagnostic pop
        {
            if (s->func_recv)
                //recv_to_fifo(i);
                //or connect_client(i);
                s->func_recv(s);
        }
    }
}

void do_parsepacket(void)
{
    for (int i = 0; i < fd_max; i++)
    {
        Session *s = session[i].get();
        if (!s)
            continue;
        if (!s->connected
            && static_cast<time_t>(TimeT::now()) - static_cast<time_t>(s->created) > CONNECT_TIMEOUT)
        {
            PRINTF("Session #%d timed out\n", i);
            s->eof = 1;
        }
        if (!s->rdata_size && !s->eof)
            continue;
        if (s->func_parse)
        {
            s->func_parse(s);
            /// some func_parse may call delete_session
            if (!s)
                continue;
        }
        /// Reclaim buffer space for what was read
        RFIFOFLUSH(s);
    }
}

void do_socket(void)
{
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wold-style-cast"
    FD_ZERO(&readfds);
#pragma GCC diagnostic pop
}

void RFIFOSKIP(Session *s, size_t len)
{
    s->rdata_pos += len;

    if (s->rdata_size < s->rdata_pos)
    {
        FPRINTF(stderr, "too many skip\n");
        abort();
    }
}